1. Field of the Invention
This invention relates to a new method for producing a high magnetic permeablility alloy film composed of iron, aluminum and silicon.
2. Description of the Prior Art
Recently, the enhancement of recording density is demanded in the field of magnetic recording technology in order to adapt to the diverse information to be recorded. Therefore, it is also demanded to obtain a magnetic head having a narrower track width and a narrower gap length, and including a material of a high magnetic permeability and a high saturation magnetization.
A Sendust alloy composed of iron, aluminum and silicon has been well known to be suitable as a magnetic head material because it has a high magnetic permeability, a high saturation magnetization and good wear resistance.
It has been well known that the magnetic permeability of an alloy of the iron-aluminum-silicon system varies largely with the composition thereof. Alloys of iron-aluminum-silicon system which show narrow and sharp peaks of magnetic permeability are known as Sendust alloys. A Sendust alloy for practical use is usually composed of 6 wt % Al, 9.5 wt % Si, and the remainder of Fe. On producing a Sendust alloy film, the control of the composition thereof is an essential problem to obtain excellent magnetic characteristics. The term "Sendust alloy" will hereinafter be referred to a high magnetic permeability alloy in a rather broad range of the composition in the iron-aluminum-silicon system.
Conventionally, the following methods have been used to produce a Sendust alloy film. (1) A process of polishing a bulk Sendust alloy into a film of a predetermined thickness. (2) A sputtering method of preparing a Sendust alloy film of a predetermined thickness. (3) A rapidly quenched method to form a Sendust alloy film. However, these methods have the following disadvantages. As for the first method, it is difficult to cut and to dice a bulk material because of the brittleness thereof. It is also difficult to precisely control the film thickness. The second method is not appropriate to form a relatively thick film because of its very slow deposition rate. Finally, the third method does not allow precise control of the film thickness because the film thickness is easily influenced by the processing conditions. The brittleness and the largeness of grain size of a rapidly quenched film remains a problem to be solved; the former causes troubles during a shaping process, and the latter limits the frequency characteristics.